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$ postmap /etc/postfix/transport $ postfix reloadNOTE : That will deliver email for user1 and user2 to [1,2]-mailserver.example.com. If you don't specify anything in the transport map, the default transport (which is usually deliver locally) will be used.

B. Configure Internal Mail Server :

The internal mail server holds the mailbox and forward all outbound mail to the DMZ mail server.